图1 功率半导体器件封装示意图[1]

Fig. 1 Schematic of typical packaging of power semiconductor device[1] (1200 V, chip area 9 mm×9 mm, encapsulated with Al2O3 DCB substrate)

图2 氮化硅陶瓷液相烧结示意图[10]

Fig. 2 Schematic of the liquid phase sintering mechanism for Si3N4 ceramics[10]

图3 玻璃相体积分数、晶界膜厚度(δ)、晶粒尺寸对β-Si3N4热导率的影响[13]

Fig. 3 Effects of volume fraction of glassy phase, grain- boundary film thickness(δ), and grain size on the thermal conductivity of β-Si3N4[13]

图4 晶格氧含量对氮化硅陶瓷热导率的影响[17]

Fig. 4 Effect of lattice oxygen content on the thermal conductivity of Si3N4 ceramics[17]

图5 以MgF2或MgO为烧结助剂制备Si3N4陶瓷的位移-温度变化曲线[19]

Fig. 5 Displacement-temperature curves of Si3N4 ceramics with MgF2 or MgO as sintering additives[19]

图6 添加不同LiF含量制备Si3N4样品的XRD谱图[20]

Fig. 6 XRD patterns of Si3N4 samples prepared with different LiF contents[20]

图7 硅酸盐液相中氟原子的解聚机理[22]

Fig. 7 Depolymerization mechanism of F atom in silicate melts[22] (a) F atom breaks the network structure by replacing the bridging oxygen atoms; (b) Solute atom solution-diffusion-precipitation mechanism during liquid-phase sintering in samples YOMO and YFMF; (c) Free energy barriers overcome by solute atoms in melts Y-Si-O-N and Y-Si-O-N-F; (d) Mechanism of solute drag effect on grain boundary migration

图8 添加不同助剂的氮化硅陶瓷气压烧结(GPS)后的SEM形貌[24]

Fig. 8 SEM morphologies of the polished surfaces of Si3N4 ceramics after gas pressure sintering (GPS) with different additives added[24] (a) MgO-doped for 2 h; (b) MgO-doped for 48 h; (c) MgSiN2-doped for 2 h; (d) MgSiN2-doped for 48 h

图9 添加Y2O3 (a)和Y2Si4N6C (b)烧结助剂的氮化硅陶瓷样品的HRTEM照片[31]

Fig. 9 Typical HRTEM images of Si3N4 ceramics added with Y2O3 (a) and Y2Si4N6C (b) as additives[31]

图10 热压试样相对位移随温度变化的曲线[32]

Fig. 10 Curves of relative displacement of the as-pressed specimens with temperature variation[32]

图11 含ZrSi2-MgO助剂的氮化硅陶瓷致密化机理示意图[36]

Fig. 11 Densification mechanism of Si3N4 ceramics with ZrSi2-MgO additive[36]

图12 Si3N4陶瓷的原位收缩曲线[10]

Fig. 12 Shrinkage curves of the Si3N4 ceramics[10]

图13 1900 ℃时Si3N4-Y2O3-SiO2体系的相图示意图[10]

Fig. 13 Schematic illustration of Si3N4-Y2O3-SiO2 phase at 1900 ℃[10]

图14 添加ZrO2、ZrH2的氮化硅陶瓷STEM-EDS表征[47]

Fig. 14 STEM-EDS characterizations of Si3N4 ceramics with the addition of ZrO2 and ZrH2[47] (a, d) Bright-field TEM images for Si3N4 ceramics with the addition of (a) ZrO2 and (d) ZrH2; (b, e) Elements distribution for Si3N4 ceramics with the addition of (b) ZrO2 and (e) ZrH2; (c) EDS analysis of the marked points in (a, d) images; (f) HRTEM image presenting the grain boundary film marked by the red rectangle in (d) image

图15 未添加(a, c)和添加(b, d)含C埋粉的氮化后样品微观形貌(a, b)和气压烧结后氮化硅微观形貌(c, d)[57]

Fig. 15 SEM images on the fracture surfaces of nitrided samples (a, b) and post-sintered samples (c, d) without (a, c) and with (b, d) graphite powder bed addition[57]

图16 PDA涂层的TEM照片及碳-氮化硅核壳结构示意图[59-60]

Fig. 16 TEM images of PDA-coated powder and schematic of Si3N4-C core-shell structure[59-60] (a, e) Overall morphologies of PDA-coated (a) and PDA-free (e) powder; (b, f) Partial magnified images of (a, e), respectively; (c, g) O distributions of PDA-coated (c) and PDA-free (g) powder; (d, h) Si and N distributions of PDA-coated (d) and PDA-free (h) powder; (i) Schematic of Si3N4-C core-shell structure

图17 氮化硅陶瓷烧结过程的(a)收缩行为和致密化机理, 以及(b)β相比例与相对密度的关系[62]

Fig. 17 (a) Shrinkage behaviors and densification mechanism of Si3N4 ceramics during sintering, and (b) relationship between β phase ratio and relative density[62]

图18 氮化硅样品的微观形貌及尺寸变化[10]

Fig. 18 Evolution of microstructure and diameter of Si3N4 ceramics[10] (a-c) Without Si addition; (d-f) With Si addition